Suprising mrad from O-like 532

[olympus mons]

In another thread a new member was asking how good the divergence is on the Crown Upgrade 400mW 532nm costing just $180. To help the man out I looked up my first review I did on LPF of this laser which was my first handheld and I was pretty pleasantly surprised. Since at the time I didn't do the equation but instead reported the data I measured. Tonight I did the maths and was shocked the divergence is even better than the company advertises. .909 mrad

1.5mm at aperture.
6mm at 2 meters
11mm at 7.5 meters = .909

Not bad for a company that gets bashed by a lot of people here. This seems above average for 532nm yes?

I'd like to next measure my Wicked Lasers Evo 532nm. This laser has the thinnest beam out of any in my collection. Id like to see how it measures up when I get some free time.
Anyway just thought I would share this as we are seeing less and less threads about lasers these days compared to off topic arguments and dramas.

 

[Sta]

Wow. That is quite nice! Does it run in TEM00?
My 500mW XPL 532 has divergence of 1.3mRad, which is pretty good considering it runs in TEM02. If this one runs in TEM00 with divergence that good I might consider buying one.

 

[InfinitusEquitas]

O-like is not bad at all, but there's a bit of a language barrier, and their lasers while usually as advertised, or close, tend to be made cheaper.

They are still 100x better vs all of the dropshippers. Their Crown Upgrade was my most powerful laser, and was very overspec, to the tune of ~550mW.

 

[steve001]

In another thread a new member was asking how good the divergence is on the Crown Upgrade 400mW 532nm costing just $180. To help the man out I looked up my first review I did on LPF of this laser which was my first handheld and I was pretty pleasantly surprised. Since at the time I didn't do the equation but instead reported the data I measured. Tonight I did the maths and was shocked the divergence is even better than the company advertises. .909 mrad

1.5mm at aperture.
6mm at 2 meters
11mm at 7.5 meters = .909

Not bad for a company that gets bashed by a lot of people here. This seems above average for 532nm yes?

I'd like to next measure my Wicked Lasers Evo 532nm. This laser has the thinnest beam out of any in my collection. Id like to see how it measures up when I get some free time.
Anyway just thought I would share this as we are seeing less and less threads about lasers these days compared to off topic arguments and dramas.

I don't think your measurement is accurate. You are a few meters short. Measure the spot diameter at 10 meters. The reason is you could still be within the Rayleigh Range (RR). Likely though you are passed it at 10m. 10 meters will give a truer result. If you are still within the RR, the beam will only expand 1.4 times it's original diameter 1.5mm = 2.1mm your beam is 6mm at 6m which seems greater than I would expect. Your beam seems to have expanded 4 times it's original diameter at 6m.

To measure, I use the protective photo frame glass. Make two straight lines that intersect like this + with tick marks in 1mm increments on both lines. Center the spot where the lines cross. I measure under bright light to reduce blooming.

 

[olympus mons]

I don't think your measurement is accurate. You are a few meters short. Measure the spot diameter at 10 meters. The reason is you could still be within the Rayleigh Range (RR). Likely though you are passed it at 10m. 10 meters will give a truer result. If you are still within the RR, the beam will only expand 1.4 times it's original diameter 1.5mm = 2.1mm your beam is 6mm at 6m which seems greater than I would expect. Your beam seems to have expanded 4 times it's original diameter at 6m.

To measure, I use the protective photo frame glass. Make two straight lines that intersect like this + with tick marks in 1mm increments on both lines. Center the spot where the lines cross. I measure under bright light to reduce blooming.

Okay I will try again with the Crown when I break out the tools to measure the Evo. Just to add I was wearing my Eagle Pair so the dot was quite defined in case that matters. In other words I wasn't measuring the spot with the naked eye aka blooming as you put it, which always looks much larger than it actually is.

Also you wrote 6mm at 6m. Not sure if that was a typo or you misread my post but it was 6mm at 2m. Which if I am understanding you correctly, this could be even more evidence that my measurement isn't accurate. 1.5mm at aperture then 6mm 2m away does sound like quite a big expansion. Thanks for the help. I need to read up on what RR is. That's new to me. I have a nice collection but I'm the first to admit I'm not very knowledgeable or technical.

edited to add- I just tried to read up on RR. Way to advanced and technical for me to understand. However, I found a PDF on how to properly measure beam divergence and Steve you are correct. My distances were not great enough. I also found an old thread that Cyparagon had some good tips such as making the first measurement at 11m and the second as reasonably far as can be measured for greater accuracy. Ill do it again at 11m and 21m at a friends house. I live in an apartment until June. We finally got a house with a big ole back yard so I can resume laser nights.

Sorry for the mis information everyone.

 

[steve001]

Okay I will try again with the Crown when I break out the tools to measure the Evo. Just to add I was wearing my Eagle Pair so the dot was quite defined in case that matters. In other words I wasn't measuring the spot with the naked eye aka blooming as you put it, which always looks much larger than it actually is.

Also you wrote 6mm at 6m. Not sure if that was a typo or you misread my post but it was 6mm at 2m. Which if I am understanding you correctly, this could be even more evidence that my measurement isn't accurate. 1.5mm at aperture then 6mm 2m away does sound like quite a big expansion. Thanks for the help. I need to read up on what RR is. That's new to me. I have a nice collection but I'm the first to admit I'm not very knowledgeable or technical.

edited to add- I just tried to read up on RR. Way to advanced and technical for me to understand. However, I found a PDF on how to properly measure beam divergence and Steve you are correct. My distances were not great enough. I also found an old thread that Cyparagon had some good tips such as making the first measurement at 11m and the second as reasonably far as can be measured for greater accuracy. Ill do it again at 11m and 21m at a friends house. I live in an apartment until June. We finally got a house with a big ole back yard so I can resume laser nights.

Sorry for the mis information everyone.

Yes, that was a typo. You could bounce the beam off a mirror to gain more distance. Do it at 10m. 10m seem to be the generally agreed upon distance to test for collimation. You can measure the beam afterwards at shorter and longer distances to see how it performs.


The RR is interesting. We all know light will expand over distance. In the case of collimating a laser into a beam we use optics, usually two optics, one to expand the beam and the other to collimate. With a given set of optics one being negative and one being positive usually, a Galilean beam expander is constructed. A Keplarian type expander use two positive lenses. There's a point after adjusting the spacing between them where the beam will have lowest divergence ( aka infinite conjugate. IC). What is actually happening is this. When optimally collimated, the optical system is forcing the beam to converge at a slightly slower rate while at the same time the wave front is expanding slightly faster and it will do so until it passes the RR. Once passed it the beam will expand in a linear fashion just like a flashlight beam. If ones uses a negative focal length lens of say 6 millimeters and a positive focal length lens of 10 millimeters the RR will be short. However, a longer positive focal length lens will create a longer RR. Check out the Gaussian Beam Propagation app https://lightmachinery.com/optical-design-center/ or scroll down to use the older archived version. Both have graphic presentation. If you need help using either let me know.

 

[olympus mons]

I did the best I could not having access to a back yard. Steve you were definitely correct which is easily shown by the numbers I got tonight. Sadly, I still don't have the divergence of these lasers because the max distance I was able to obtain in this stupid apartment was 10 meters. (we are moving into our new home next month thanks god). So I took measurements from 7 meters and 10 meters. Sorry guys that's the best I could do at this time. I measured 4 different 532's. If you could make sense of the inconsistency of my results I would appreciate it. I'm pretty frustrated atm. Mostly because I hate living in an apartment in the city and feel like I just wasted my time. But I do think I will learn something from this. Hopefully.
The crown does have a really nice beam. Maybe Ill be able to get the actual divergence when we move house. My TI died on the last measurement and its not the battery. It was flickering quite a bit and spot was a mess towards the end but i did get it measured before it died.


Evo-150mW 8mm @ 7m 12mm @ 10m
Crown Up- 400mW 11mm @ 7m 11mm @ 10m
TI- 100mW 13mm @ 7m 14mm @ 10m
Spartan 200mW 13mm @ 7m 13mm @ 10m

So my questions are The Evo was the only laser that seemed to make sense. Was this because it had less RR effect? From looking at this data would you conclude the Evo has the nicest beam?

I tried inserted some pics but the files are too big all except for this one for some strange reason. I'm tired, cranky, out a laser and don't feel like re-sizing them tonight. I slightly bumped the table so that's why the spots are a bit off in the pic.

 

[steve001]

Evo-150mW 8mm @ 7m 12mm @ 10m
Crown Up- 400mW 11mm @ 7m 11mm @ 10m
TI- 100mW 13mm @ 7m 14mm @ 10m
Spartan 200mW 13mm @ 7m 13mm @ 10m

So my questions are The Evo was the only laser that seemed to make sense. Was this because it had less RR effect? From looking at this data would you conclude the Evo has the nicest beam?

Based upon your measurments the Crown Up which showed no change in diameter has the lowest divering beam. That means the RR a greater than 10m which is good if one wants a small spot at distance. To find out what distance the RR stops and the beam starts to expand like a flashlight's beam for the Crown Up or any of them, measure when you can the beam at greater distances. One or two meters increments is good. I suspect the RR isn't greater than 20m. Only further measurements will tell.

 

[Benm]

With these single modes tests at 10m or so ranges are fine.

You start to see the real issue wilt things like multimode 445s that can be focussed to an acceptably 'round' (or sqaure) dot within a couple of meters. 100 meters away this transforms into a fairly thin line as you really see the fast axis overtaking the slow there.

Single mode lasers have this property to, but it's generally not that annoying as the beam pattern stays roughly circular regardless of the distance and the divergence is about as bad as the slow axis on a multimode, no where nearly as bad as the fast axis.

 

[olympus mons]

Went to my buddies house and got the second measurements at 18 meters. The mrads are as follows

CROWN UPGRADE - 400mW 532 nm 1.124 mrad
SPARTAN - 200mW 532 nm 1.744 mrad
EVO - 200mW 532 nm 1.124 mrad

I'd also like to add the spot quality was best on the spartan. The crown was pretty messy buy I'm very sure the lens could use a good cleaning. Been camping twice and no cap to protect it.

 

[InfinitusEquitas]

I hope you got the diffraction gratings that go with the Crown. If not, definitely order a set, they are fun to have around.